Partly true. 3K/4K carbs will bolt onto a 2TB twin carb manifold, the single carb has a bigger spacing though. Other supposed direct swaps are Datsun L16 and L18 carbs and some Mitsi vans I believe.
yeah ive compared the mitsi L300 carb. its an aisan too but slightly different design. bolt pattern same. can send some comparison pics if you wish.
its bigger than 4k and 5k carb. think its something like 23/28 venturii compared to 4k's 21/24 or 21/25. 5k have something like 21/26(?)
yea i measured the 4k and twin 2t - and both are around 52mm x 87mm. now it will b easy to get 2 plates to fit 2 webers onto my 2t manifold, if i just say for a 4k.